Conventionally, an electronic device chiefly provides only one specific function, but has become able to provide a variety of functions with the gradual developments of technology. Accordingly, a user interface (UI) for enabling a user to easily use the electronic device having the various and complicated functions is gradually becoming important.
A gesture-based UI for manipulating an electronic device based on only a users gesture without an additional input device, such as a remote controller, is recently emerging as a core technological field. According to this tendency, active research is being done on the gesture-based UI for a key input which is basically necessary in order to utilize the various functions of an electronic device.